Behaviour and neural correlates in an implicit confidence task

Objective: Methods for measuring the confidence with which people make decisions, have traditionally relied on post-decision self-reports. These studies of confidence have found neural correlates of confidence in several areas including rostrolateral prefrontal cortex (De Mar0no et al., 2013), dorsal and anterior medial prefrontal cortex, bilateral orbitofrontal gyrus, and bilateral striatum (Molenberghs et al., 2016). However, it is not clear if the knowledge of an upcoming confidence report influences the decisions, and/or the neural representation of confidence. In a previous study we have presented a task that can measure implicit decision confidence, and shown that this measure is strongly correlated with an explicitly measured decision confidence. In the present study, participants performed the same task while undergoing functional magne0c resonance imaging (fMRI) scanning to investigate if the neural correlates of implicit confidence differs from those of explicitly measured confidence as identified in previous studies. Methods: Thirty-nine participants performed the deceit-free task where they have to move a cursor around a circle to catch particles that move from the centre to the edge of the circle. The direction of the particles is block-wise determined by a mean and a standard devia0on from that mean. The participants can change the size of the cursor, and the amount of points rewarded for each catch is inversely proportional to the size of the cursor. After performing the task in the scanner, participants performed a control task and a Balloon Analogue Risk Task outside the scanner. Results: The fMRI analysis showed activation in the expected decision-making areas (including the striatum, thalamus, anterior insula and ventromedial prefrontal cortex) as well as in areas associated with spa0al tracking. The analysis also revealed correla0on with confidence signals in anterior cingulate cortex and correla0on with changes in confidence in anterior premotor cortex as well as both sides of posterior parietal cortex. Conclusion: We believe that there is a case for developing methods for measuring confidence implicitly, and our results show that not only could such a task work successfully, but also that the neural correlates might be different from the correlates found in a task measuring confidence explicitly.